GENERAL OBJECTIVE: To determine the long-range hazard, in terms of carcinogenesis, of radiotherapy and chemotherapy used in treatment of Hodgkin's disease. SPECIFIC AIMS: (1) To determine the incidence of second primary malignancies in patients treated with modern modalities for primary Hodgkin's disease. (2) To determine the variation in incidence of second primary malignancies by modality of therapy for primary Hodgkin's disease, comparing - (a) No intensive treatment; (b) Intensive radiotherapy alone: (c) Intensive chemotherapy alone; (d) Intensive both. (3) To determine the variation in incidence of second primary malignancies by specific drugs used in treatment of Hodgkin's disease. (4) To determine the variation in incidence of second primary malignancies by time since initiation of therapy for Hodgkin's disease. (5) To determine the distribution by organ site of second primary malignancies. (6) To determine the variation in incidence of second primary malignancies as in aims (1), (2), (3), and (4) above for all cancers, for leukemias only, and for all cancers other than leukemia. METHODS: A cohort study is planned, using retrospective data on patients treated in 1940 to 1975 and followed to 1980 or death before 1980 and using prospective data on these same patients followed to 1984. Patients with Hodgkin's disease will be ascertained through registration records of large cancer therapy centers. The total study population will consist of 3000 patients (1500 diagnosed before 1970 and 1500 diagnosed in 1970-75).